How I can execute server side function ( result boolean) from javascript code?

The only ways to execute a server-side method from the client-side (JavaScript) is to either do a PostBack or use AJAX.

NC...

Like this...

 ASPX Code

The following valFileName2_ClientValidate() javascript method calls on a C# method called IsFilenameAllowed().
This was used in conjunction with a custom validator which we wanted to code in C#, but needed to call without postback (due to us using a fileupload control, which cant' exist in an update panel, and would be unwieldy due to the file uploading before validation could take place.

You can find other examples here: http://www.codeproject.com/KB/aspnet/JavaScriptAndServerEvents.aspx
and here: http://www.eggheadcafe.com/community/aspnet/17/10010151/calling-c-method-from-ja.aspx

function valFileName2_ClientValidate(source, args)
               {
	                // requires an AJAX scriptmanager on your page
                                // format is:
                                // PageMethods.[serverside_method_name](args.Value, [javascriptcompletemethod],[javascriptfailedmethod], args)
                                PageMethods.IsFilenameAllowed(args.Value, valFileName2_OnComplete, valFileName2_OnError, args);
               }
               
                function valFileName2_OnComplete(returnObj, userContext)
                {
                    for(var i = 0; i < Page_Validators.length; i++)
                    {
                        if(Page_Validators[i].id == "<% = valFileName2.ClientID %>")
                        {
                            if(returnObj)
                            Page_IsValid = false;
                            Page_BlockSubmit = true;
                            Page_Validators[i].isvalid = returnObj;
                            ValidatorUpdateDisplay(Page_Validators[i]);
                            return;
                            
                        }
                    }
                }
               
                function valFileName2_OnError(returnObj, userContext)
                {
                }

Code Behind (C#)

// mark your methods with [WebMethod] to allow javascript accessibility

        [WebMethod]
        public static bool IsFilenameAllowed(string filePath)
        {
            // do some stuff here
            return soemthinghere;
        }

Of corurse i want use AJAX, but how?

I have a javascript function that open a window modal if a server side function retuns true.

The server side function execute a complex sql instructions.

Thanks

You can use PageMethod from javascript. You have to make a server side method as Web method.

Here is the sample code in this link below.

http://www.geekzilla.co.uk/View30F417D1-8E5B-4C03-99EB-379F167F26B6.htm

Hope this will help.

Yaler:

How I can execute server side function ( result boolean) from javascript code?

hope this one help a little bit

assume that you have a js function  in you js file

function CheckFeedBack(id)
{ ...

// do whatever you want to check

if (id=='btnSubmit')
    {

       doPostBack('btnSubmit','OnClick');

   }

}

and you code you have something like this in your cs page load

Page.GetPostBackEventReference(btnSubmit);

if (!Page.IsPostBack)

{

btnSubmit.Attributes.Add("onclick", "CheckFeedBack('btnSubmit');return false;");

}

............. 

protected void btnSubmit_Click(object sender, EventArgs e)
{

...//server side function

}

Thanks the pagemethod is a good solution.